Project Summary/Abstract Although families with children with intellectual and developmental disabilities (IDD) experience heightened family conflict, stress and risk for adjustment problems, few evidence-based programs exist to support them. Programs are rarely adapted to these families? specific needs, and the available interventions are not empiri- cally-based or rigorously evaluated. Existing programs fail to address the family system, often ignoring the well-being of parents and typically developing (TD) siblings. A critical need exists for an evidence-based pro- gram to ameliorate the impact of family stress and conflict on the overall well-being of parents and TD siblings, as well as individuals with IDD. Our objective in this proposal is to test the efficacy for parents, TD siblings, and children with IDD of an adaptation of the psycho-educational and communication training approach used in a previously validated prevention/intervention program for community families, and to examine the mechanisms associated with change processes that occur as a result of the 4-week program. Our long-term goal is to in- crease the availability and affordability of empirically-supported family-systems approaches to reduce family stress and conflict in families of individuals with IDD. Our central hypothesis is that participation in the program will support the identified needs of families with a child with IDD, improve the well-being and adjustment of par- ents, increase emotional security and adjustment for TD siblings, and be associated with improvements in adaptive functioning for individuals with IDD. This central hypothesis is supported by promising qualitative evi- dence and preliminary analyses from an ongoing pilot study using the adapted curriculum included in the pre- sent proposal. Our rationale is that providing a family-systems approach to improving the family environment will support the well-being of each family member, including the child with IDD. The specific aims are: (1) de- termining the efficacy of the program for parents, (2a) determining the efficacy of the program for typically de- veloping siblings, (2b) testing process models, guided by the Emotional Security Theory (EST; Davies & Cum- mings, 1994), to explain how and why and for whom and when changes occur as a result of the program, and (3) examining the impact of the program on individuals with IDD. Families (n=150) that include a child with IDD and a TD sibling between 11 and 17 years of age, will be randomly assigned to one of two groups: (1) parent and typically developing sibling intervention, or (2) resource only control. Multi-method assessments of all fami- ly members will be obtained at pre- and post-intervention visits, and 6-month and 1-year follow-ups. The ap- proach is innovative because it addresses multiple family members? needs, tests theory about explanatory models for program impact, and utilizes a brief, psycho-educational format and a RCT design to evaluate its efficacy. This research is significant because it will create an inexpensive model program for family-system- level interventions for families of children with IDD, benefiting parents, siblings and the child with IDD, including evaluations of program effectiveness in standing community centers.